You make a good point there, if she is in stage 1 rampancy it also could of happened when she was left on High Charity with the Gravemind. Either way, by Halo 4 she is likely already in stage 1of rampancy. Of course it's possible that she could skip it entirely, but given what she went through on High Charity and the Forward Unto Dawn, it's safe to assume that she is well into stage 1.